1. Field of the Invention
The present invention relates generally to lifting devices and more specifically to a carrier for lifting devices having a variable width track which allows the track of the wheels to be changed while the carrier is transporting a load.
2. Discussion of the Prior Art
Many times it is advantageous for the width of a lifting device or the like to be as small as possible for entrance through gates and other narrow constraints. However, a lifting device with a narrow width is not appropriate for handling loads. Further, derricks and other lifting devices with variable tracks are nothing new. U.S. Pat. No. 3,754,361 to Branham, U.S. Pat. No. 3,712,398 to Althaus, and U.S. Pat. No. 5,489,114 to Ward all disclose devices having a variable track. The drawback to all these variable tracks is their inability to actuate while the carrier is moving. The carrier must be put on jacks, so that the wheels may be actuated inward or outward. The extra step of elevating the lifting device on jacks is time consuming and provides an extra opportunity for an accident to occur.
Accordingly, there is a clearly felt need in the art for a carrier for lifting devices having a variable width track which allows the track width to be changed while moving with the lifting device and when the carrier is transporting a load.